Complex regional pain syndrome with selective emotional sudomotor failure

We report a patient with sympathetically maintained pain following a mild limb injury. Only emotional sudomotor failure was found in the painful limb. Thermoregulatory vasomotor function was intact. However, the patient had other target-specific sympathetic lesions, including thermoregulatory vasomotor failure in a different limb, not associated with pain. We hypothesize that the sympathetic failure preceded the symptoms and that the mild injury may have provoked collateral sprouting of emotional sudomotor fibres, coupling them with somatic sensory fibres to cause continuous pain.